1. Field of the Invention
The present invention relates to a lens supporting mechanism for a camera. In particular, the present invention relates to the mechanism to fix a lens supporting barrel supporting a lens group to a movable barrel that is driven in a direction of an optical axis.
2. Background and Material Information
A lens shutter camera may be provided with a shutter unit that is arranged between or behind lens groups of a photographing lens. Since the lens group comprises a plurality of lenses, generally they are installed in a lens supporting barrel. In the case where at least one of the lens groups are driven along an optical axis together with the shutter unit, i.e., the photographing lens is a zoom lens or the photographing lens can be switched between a retracted position and a photographing position, the lens group and the shutter unit are arranged on a movable barrel.
In the conventional lens shutter camera, the lens supporting barrel for a front movable lens group is fixed to the shutter unit at the rear side of the lens supporting barrel, and the shutter unit is fixed to the movable barrel at the rear side thereof. Alternatively, the lens supporting barrel is fixed to the movable barrel at the front side thereof and the shutter unit is fixed to the movable barrel at the front side thereof.
According to the conventional structures, an accurate alignment of the lens supporting barrel with the movable barrel is difficult because of a cantilever support for the lens supporting barrel. That is, when the lens supporting barrel is fixed to the shutter unit, the lens supporting barrel is only supported at the rear side. On the other hand, when the lens supporting barrel is fixed to the movable barrel at the front side, the lens supporting barrel is only supported at the front side. In either case, the positional relationships may be changed.
Furthermore, when a camera is provided with a zoom lens having front and rear lens groups, it is necessary to make optical axes of the lens groups coaxial. However, the front lens group and the rear lens group, which are driven along an optical axis respectively during zooming operation, are guided by the different guide mechanisms in a conventional camera, and it is difficult to keep the coaxial condition during zooming operation.